Devshirmeh
Devshirmeh was the system of the collection of young boys from conquered Christian lands by the Ottoman sultans as a form of regular taxation in order to build a loyal slave army (formerly largely composed of war captives) and the class of (military) administrators called the "Janissaries", or other servants such as tellak in hamams. The word devşirme means "collecting, gathering" in Ottoman. Boys delivered to the Ottomans in this way were called ghilmán or acemi oglanlar ("novice boys").
Read more about this topic: History Of The Eastern Orthodox Church Under The Ottoman Empire